Muscarinic agonists

ABSTRACT

Substituted 1,4,5,6 -tetrahydropyrimidine compositions, substituted 1,2,3,6 -tetrahydropyrimidine compositions and substituted 3,4,5,6 -tetrahydropyridine compositions are disclosed. They are useful for stimulating muscarinic receptors including, for example, treating the symptoms of cognitive disorders, especially impaired memory, which are associated with decreased acetylcholine synthesis and cholinergic cell degeneration.

This is a continuation of application Ser. No. 07/996,049, filed on Dec.23, 1992, now abandoned, which is a continuation of application Ser. No.07/750,504, filed Aug. 27, 1991, now U.S. Pat. No. 5,175,166.

TECHNICAL FIELD

This invention relates to drugs and more specifically the inventionrelates to heterocyclic drug compositions containing carbon and nitrogenatoms in the ring. Even yet more specifically the present inventionrelates to substituted 1,4,5,6-tetrahydropyrimidine compositions,substituted 1,2,3,6-tetrahydropyrimidine compositions, and substituted3,4,5,6-tetrahydropyridine compositions.

The invention also relates to treating mammals with such compositions.Further, the invention also relates to pharmaceutical preparationscomprising such compositions and a suitable carrier.

BACKGROUND ART

The neurotransmitter acetylcholine mediates a variety of responseswithin the central nervous system and plays an important role in memoryfunction and cognition. Cholinergic responses are mediated by muscarinicand nicotinic receptors throughout the brain, although it is acceptedgenerally that receptors in the cerebral cortex and hippocampus areassociated with memory and cognitive function. Agents that blockacetylcholine activity at muscarinic receptors and lesions ofcholinergic projections to the cortex and hippocampus impair memory andcognition.

In humans, the nucleus basalis of Meynert is the source of acetylcholinefor the cerebral cortex and hippocampus. The cholinergic cells withinthe basal nucleus degenerate in Alzheimer's disease, a disorder that isassociated with memory dysfunction and progressive cognitive decline.Current therapeutic approaches for Alzheimer's disease include treatmentwith agents that increase levels of acetylcholine or mimic the effectsof acetylcholine at receptors.

Efforts to increase acetylcholine levels have focused on increasinglevels of choline, the precursor for acetylcholine synthesis, and onblocking acetylcholinesterase (AChEase), the enzyme that metabolizesacetylcholine. The first approach, using either choline orphosphatidylcholine, has not been very successful althoughacetylcholinesterase inhibitors have shown some therapeutic efficacy.Clinical trials with these compounds have documented some improvementsin cognitive function and ability to conduct daily tasks. Majordrawbacks with AChEase inhibitors include toxicity and the side effectsassociated with activation of receptors in the peripheral nervoussystem.

Recent efforts have focused on treating Alzheimer's patients withagonists for muscarinic cholinergic receptors. Natural products, such asthe arecoline and pilocarpine ligands, can mimic the effects ofacetylcholine at receptors in the central nervous system and reversecognitive impairments in experimental animals. The clinical applicationof such ligands is hampered however by the low intrinsic activity ofthese compounds and their rapid metabolism. Other muscarinic agonistswith higher efficacy are not suitable due to either low bioavailabilityor profound side effects associated with peripheral activity.

Recent molecular biological studies have cloned five subtypes ofmuscarinic receptors, each with a unique amino acid sequence,tissue-specific expression, ligand binding profile and associatedbiochemical response. Each subtype is expressed within the centralnervous system, although m1, m3 and m4 receptors predominate in thecerebral cortex and hippocampus. In peripheral tissues, the heartexpresses m2 receptors while m3 receptors are found in exocrine glands.Pirenzepine, AF-DX 116 and p-F-hexahydrosiladifenidol are selectiveantagonists for M₁, M₂ and M₃ receptors respectively. Three subtypes(m1, m3 and m5) couple selectively to the stimulation ofphosphoinositide metabolism while m2 and m4 more efficiently inhibitadenylyl cyclase.

In addition to the recent studies showing the preferential localizationof M₁ receptors in the cerebral cortex and hippocampus, recent findingsalso show that M₁ antagonists, such as pirenzepine, produce memoryimpairments in experimental animals.

Thus, it will be appreciated by those skilled in the art that what isneeded in the art to reverse the cognitive and memory deficitsassociated with a loss of cholinergic neurons, as found in Alzheimer'sdisease, is a selective muscarinic agonist with high central nervoussystem activity. This agonist should bind selectively to M₁ muscarinicreceptors, localized predominantly in the cerebral cortex andhippocampus. It should stimulate phosphoinositide metabolism in thehippocampus.

Even more broadly, however, there is a need in the art to providemuscarinic agonists which have activity at various muscarinic receptorsubtypes in the central and peripheral nervous system.

DISCLOSURE OF THE INVENTION

It is an object of this invention to satisfy the above described needsin the art. In accordance with one aspect this invention an M₁ selectivemuscarinic agonist with high central nervous system activity isprovided. In accordance with a broader aspect, therapeutic benefits areprovided by providing improved compositions which stimulate muscarinicreceptors.

The object of this invention is accomplished by providing compoundshaving the formula (i), (ii) or (iii) set forth below or apharmaceutically acceptable salt thereof: ##STR1## In the above: A is Hor NHR; R is H, an alkyl of 1-8 carbon atoms, preferably 1-4, and mostdesirably, 1-3 carbon atoms, --C(O)--R¹ or --C(O)OR¹ ; Z is --C(O)OR¹,or --OC(O)R¹, or ##STR2## wherein X is O or S, and wherein R¹ is amonovalent hydrocarbon radical having 1-8 carbon atoms, preferably 1-4,and most desirably, 1-3 carbon atoms, R₂ is alkyl of 1-8 carbon atoms,preferably 1-4, and most desirably, 1-3 carbon atoms, alkylthioalkyl ofup to 8, preferably up to 3 or 4, carbon atoms, alkoxyalkyl of up to 8,preferably up to 3 or 4, carbon atoms or NHR, R³ is H or --CH₃, R₄ is Hor an alkyl of 1-8 carbon atoms and wherein R⁵ is H, an alkyl of 1-8carbon atoms, alkoxy of 1-8 carbon atoms or an alkylthio group of 1-8carbon atoms. Suitably, R⁴ and R⁵ will contain 1-4 carbon atoms,preferably 1-3. The monovalent hydrocarbon radical may, for example, bean alkyl, an alkaryl, an aryl, an aralkyl, an alkenyl or alkynylradical.

Exemplary of highly desirable inventive compounds, and theirpharmaceutically acceptable salts are:5-methoxycarbonyl-1,4,5,6-tetrahydropyrimidine;5-acetoxy-1,4,5,6-tetrahydropyrimidine;1-methyl-5-methoxycarbonyl-1,2,3,6-tetrahydropyrimidine;2-amino-5-methoxycarbonyl-3,4,5,6-tetrahydropyridine;5-ethoxycarbonyl-1,4,5,6-tetrahydropyrimidine; propynyl1,4,5,6-tetrahydropyrimidine-5-carboxylate;5(3-methyl-1,2,4-oxadiazol-5-yl)-1,4,5,6 tetrahydropyrimidine. Alsohighly desirable are those compounds where Z is moiety I, II, III, IV,and VI, especially I, for example, with structure (i) as a nucleus.

In another aspect, the present invention provides an improvement inmethods for providing a therapeutic benefit to mammals, for example,those having a cholinergic deficit comprising administering to suchmammal, in any convenient manner, a non-toxic amount, but an amounteffective to stimulate muscarinic receptors, of a compound as describedabove, or a pharmaceutically acceptable salt thereof.

In yet another aspect of this invention, pharmaceutical preparations areprovided which include amounts effective to stimulate cognitive functionof a compound as described above, or pharmaceutically acceptable saltthereof, along with a pharmaceutically acceptable solid or liquidcarrier.

It will, of course, be apparent to those skilled in the art that whenreference is made to the compounds, or salts, of this invention, suchterminology includes within its scope the various forms of suchcompounds, and salts. Thus such terminology includes the variousstereoisomers and, for example, various tautomeric forms. It alsoincludes forms which when administered into the body form suchcompositions.

DETAILED DESCRIPTION INCLUDING THE BEST MODE OF CARRYING OUT THEINVENTION Theraputic Use

It will be apparent that the use of the compounds in accordance withthis invention, by virtue of the basic nitrogen in thetetrahydropyridine and the tetrahydropyrimidine rings may be employed inthe form of their pharmaceutically acceptable salts. The salts will beformed in a known conventional manner and the preferred salts areorganic acid or an inorganic acid addition salts. Examples of suitableacids for the formation of pharmaceutically acceptable acid additionsalts are hydrochloric, sulfuric, phosphoric, acetic, trifluoro acetic,benzoic, citric, malonic, salicylic, malic, fumaric, oxalic, succinic,tartaric, lactic, gluconic, ascorbic, maleic, aspartic, benzenesulfonic,methane and ethanesulfonic, hydroxymethane and hydroxyethanesulfonicacids and the like. Further particulars can be had by reference to theJournal of Pharmaceutical Science, 66 (1) 1-19 (1977).

In the discussion which follows, including the examples and claims,unless otherwise expressly indicated, when reference is made to anycompound of the present invention, the term compound includes,therefore, any pharmaceutically acceptable salt thereof and forms whichrelease substantially the same active moiety as said compound or salt.

In therapeutic uses as agents for treating cholinergic insufficiency,the compounds utilized in the pharmaceutical method of this inventionare desirably administered to the patient in amounts effective tostimulate muscarinic receptors and thereby stimulate central and/orperipheral nervous systems. Since the compounds of this invention willstimulate central muscarinic acetylcholine receptors they are usefulwhen administered in effective amounts, to treat not only presenile andsenile dementia but also Huntington's chorea, tardive dyskinesia,hyperkinesia, mania and Tourette syndrome. In effective amounts, theyare also useful as analgesics, for example, in treating painfulconditions like rheumatism, arthritis and terminal illness and they areuseful in the peripheral nervous system to treat glaucoma and atonicbladder conditions. The effective amounts vary but usually translate todosage levels of from about 0.7 to about 7000 mg per day. For a normalhuman adult of approximately 70 kg of body weight this translates into adosage of about from 0.01 to 100 mg/kg of body weight per day. Thespecific dosages employed, however, may vary depending upon therequirements of the patient, the severity of the condition being treatedand the activity of the compound being employed. The determination,however, of optimum dosages for any particular situation is well withinthe skill of the art.

In preparing pharmaceutical compositions of the compounds (or theirpharmaceutically acceptable salts) of this invention, inert, solid orliquid pharmaceutically acceptable carriers will be employed. Solid formpreparations include powders, tablets, dispersable granules, capsules,cachets, and suppositories.

A solid carrier can be one or more substances which may also act asdiluents, flavoring agents, solubilizers, lubricants, suspending agents,binders, or tablet disintegrating agents; it can also be anencapsulating material.

In powders, the carrier is a finely divided solid which is in a mixturewith the finely divided active component. In tablets, the activecompound is mixed with the carrier having the necessary bindingproperties in suitable proportions and compacted in the shape and sizedesired.

For preparing suppositories, a low-melting wax such as a mixture offatty acid glycerides and cocoa butter is first melted, and the activeingredient is dispersed therein by, for example, stirring. The moltenhomogeneous mixture is then poured into convenient sized molds andallowed to cool and solidify.

Powders and tablets preferably contain between about 5 to about 70% byweight of the active ingredient. Suitable carriers are magnesiumcarbonate, magnesium stearate, talc, lactose, sugar, pectin, dextrin,starch, tragacanth, methyl cellulose, sodium carboxymethyl cellulose, alow-melting wax, cocoa butter, and the like.

The term "preparation" is intended to comprehend within its scope aformulation of the active compound with encapsulating material as acarrier, thereby providing a capsule in which the active component (withor without other carriers) is surrounded by a carrier and is thus inassociation with it. In a similar manner, cachets are also included.

Tablets, powders, cachets, and capsules can be used as solid dosageforms suitable for oral administration.

Liquid form preparations include solutions suitable for oral orparenteral administration, or suspensions, and emulsions suitable fororal administration. Sterile water solutions of the active component orsterile solutions of the active component in solvents comprising water,ethanol, or propylene glycol are mentioned as examples of liquidpreparations suitable for parenteral administration.

Sterile solutions can be prepared by dissolving the active component inthe desired solvent system, and then passing the resulting solutionthrough a membrane filter to sterilize it or, alternatively, bydissolving the sterile compound in a previously sterilized solvent understerile conditions.

Aqueous solutions for oral administration can be prepared by dissolvingthe active compound in water and adding suitable flavorants, coloringagents, stabilizers, and thickening agents as desired. Aqueoussuspensions for oral use can be made by dispersing the finely dividedactive component in water together with a viscous material such asnatural or synthetic gums, resins, methyl cellulose, sodiumcarboxymethyl cellulose, or other suspending agents known to thepharmaceutical formulation art.

Preferably, the pharmaceutical preparation is in unit dosage form. Insuch form, the preparation is divided into unit doses containingappropriate quantities of the active component. The unit dosage form canbe a packaged preparation, the package containing discrete quantities ofthe preparation, for example, packeted tablets, capsules, and powders invials or ampoules. The unit dosage form can also be a capsule, cachet,or tablet itself.

Representative Compounds of the Invention, Their Synthesis andProperties

Representative of the alkyl, alkoxy and alkylthio groups from which thevarious R substituents on structures (i), (ii) and (iii) will beselected in forming compounds of the present invention are methyl,ethyl, propyl, butyl and its various isomers, methoxy, ethoxy, propoxy,hexoxy as well as, for, example, methyl, ethyl and propylthio groups.Representative of the aryl, alkaryl, aralkyl, alkenyl and alkynyl groupsfrom which R¹ may be selected on those structures are phenyl (aryl),methylphenyl (alkaryl), phenylmethyl (aralkyl), ethenyl and propenyl(alkenyl) as well as ethynyl and propynyl, i.e. propargyl (alkynyl).Representative of alkylthioalkyl radicals are methylthioethyl andethylthiopropyl whereas methoxypropyl and ethoxymethyl arerepresentative of alkoxyalkyl radicals. Equivalent moieties, forexample, those presenting no steric hindrance complications, will beselected by those skilled in the art. It is preferred that the R¹hydrocarbon radical be an alkyl radical of one or two carbon atoms.Preferably the hydrocarbon radical will not be propyl, isopropyl orbenzyl.

Representative of the muscarinic agonist having high central nervoussystem activity as contemplated by the present invention and which willselectively bind to M₁ muscarinic receptors and stimulatephosophoinositide metabolism in the brain are those of the above withthe following structures: (ii) and wherein R is CH₃ and Z is C(O)OCH₃,that is, 1-methyl-5-methoxycarbonyl-1,2,3,6-tetrahydropyrimidine; (i)wherein R is H, Z is OC(O)CH₃ and wherein A is H, that is,5-acetoxy-1,4,5,6-tetrahydropyrimidine; (iii) wherein R is H and whereinD at the 5 position is C(O)OCH₃ and wherein D at the 6 position is H,that is, 2-amino-5-methoxycarbonyl-3,4,5,6-tetrahydropyridine; (i)wherein A is H, R is H and Z is --C(O)CCH₃, that is,5-methoxycarbonyl-1,4,5,6-tetrahydropyrimidine; (i) wherein Z is--C(O)OC₂ H₅, A is H and R is H, that is,5-ethoxycarbonyl-1,4,5,6-tetrahydropyrimidine; (i) wherein Z is moietyVI and X is S and R⁵ is alkoxy and A is H and R is H; (i) wherein Z isI, R² is methyl and A is H and R is H; (i) wherein Z isgamma--propynyloxycarbonyl and R and A are H.

Compounds of the present invention are prepared by the schematicallydepicted chemical reaction sequences (I-XXXVII) below.

Schematic sequence I (a) and (b) illustrate the production of compoundsof structures (i) and (iii) above. In this reaction sequence, a properlysubstituted pyridine or pyrimidine is catalytically reduced to thetetrahydro derivative and then alkylated to those structures. Startingwith a pyrimidine reactant, compounds of structure (ii) are produced bythe schematic sequence II (a) and (b). This sequence first involves analkylation to produce a quaternary compound which then is subjected to asodium borohydride reduction to produce a desired structure.

In this description of the reaction sequences, the term alkylation (ordealkylation), for simplicity, is used not only to refer to theintroduction (or removal) of an alkyl radical into a molecule but alsothe introduction (and removal) of other monovalent hydrocarbon radicals,e.g. alkaryl, aryl, araalkyl, alkenyl etc., into a molecule.

Compounds of structure (i) and (iii) or compounds of structure (ii) canrespectively be produced in accordance with reaction sequences III andIV respectively by starting with a properly substituted acyl pyridine oracyl pyrimidine. According to reaction sequence III (a) and (b), theacyl pyridine or pyrimidine in reaction sequence III (a) will becatalytically reduced to form the tetrahydro derivative. This tetrahydroderivative will be alkylated (III b) followed by reaction with an acyloxamine to thereby form the acyl oxime. In accordance with reactionsequence IV (a) and (b), compounds of structure (ii) will be formed byfirst of all reacting the substituted pyrimidine with an acyl oxaminefollowed by alkylation (IV a) to form the quaternary compound which issubjected to sodium borohydride reduction (IV b) to produce structure(ii).

Reaction sequence V a,b,c produces compounds of structure (i) bystarting with a hydroxy diamino propane. The hydroxy diamino propane isfirst subjected to a condensation reaction (V a) with a formate orcarbamate and the reaction product is esterified with an organic acid (Vb). The 1,4,5,6-tetrahydropyrimidine ester is then subjected toalkylation (V c) to produce compounds (i).

Structures (i) and (iii) are produced by reaction sequences VIII, XII,XIII and XIV. In reaction sequence VIII, a properly substituted bromopyridine or pyrimidine is subjected to halogen--metal exchange followedby carboxylation and esterification to produce the pyridine orpyrimidine ester. The ester (sequence XII) is then subjected tocatalytic reduction followed by alkylation (XIII) to produce a protectedtetrahydro ester. Structures (i) and (iii) are produced from that esterby sequence XIV. Sequence XIV shows a procedure, in which a properlysubstituted amidoxime, or a hydroxy guanidine (or sulphur analogsthereof), is reacted, under basic catalysis (sodium hydride), with theprotected tetrahydro ester to produce the (i) or (iii) structures.

Sequence XV shows the deprotection or dealkylation of the products ofsequence XIV to produce compound structures (i) when Y is NR', R' istrityl or C(O)OR (with R being a monovalent hydrocarbon of 1-7 carbonatoms) in such products.

Chemical structures (i) and (iii) can be formed in accordance withreaction sequence VI and VII. The brominated pyridine or pyrimidine isfirst subjected to halogen-metal exchange and carboxylation followed bycatalytic reduction (VI) to produce the acid. This acid is thenesterified (VII) in the presence of thionylchloride and then alkylatedto produce compounds (i) and (iii).

Structure (ii) can be produced by reaction sequences VIII, IX and X. Aspreviously described, reaction sequence VIII is used to form thepyridine or pyrimidine ester. This ester is then subjected to alkylation(IX) to form a quaternary compound and this quaternary compound is thenreduced (X) to compounds of structure (ii).

Steps VIII, XI and XVII can also be employed to produce compounds ofstructure (ii). The pyrimidine ester of step VIII is, under basiccatalysis (NaH), reacted with a properly substituted amidoxime orhydroxyguanidine (or sulphur analog thereof), as indicated in step XI,to form a pyrimidine having oxadiazole or thiadiazole substitution. Thatsubstituted pyrimidine is then (step XVII) subjected to quaternizationand borohydride reduction to produce compounds of structure (ii).

Compounds of structure (ii) can also be formed in accordance withreaction sequence XVI and XVII. In this sequence, a pyrimidine thioamideis subjected to condensation with a substituted ortho amide and thencyclized by amination with, for example, hydroxylamine-O sulfonic acid(step XVI). This is followed in turn by step XVII as described above.

Compounds of structure (ii) can be formed by reaction sequence XXXIV andcompounds (i) and (iii) can be formed by reaction sequences XXXV andXXXVI. In reaction sequence XXXIV, pyrimidine aldehydes are converted tooxathiolanes or dioxolanes by a process which involves dehydration usinga properly substituted glycol or a thiol followed by quaternization andthen sodium borohydride reduction. Compounds (i) or (iii) aresequentially produced (step XXXV) by catalytic reduction of the pyridineor pyrimidine aldehyde and alkylation to produce the3,4,5,6-tetrahydropyridine or the 1,4,5,6- tetrahydropyrimidinestructure. The tetrahydropyridine or the tetrahydropyrimidinecompositions are then subjected to dehydration with a properlysubstituted glycol or thiol (step XXXVI) to produce compounds (i) and(iii).

Compounds (i) and (iii) can also be produced by the reaction sequence ofsteps XIX, XXI, and XXIV and compounds of structure (i) can also beproduced by sequence XIX, XX, XXII and XXV. Compounds of structure (ii)can be produced by reaction sequence XIX, XXI and XXIII. The initialreaction in forming these compounds is a Strecker synthesis (XIX) toform the amino nitrile intermediate. In sequence XXI, the amino nitrilecompound is subjected to cyclization using sulfur monochloride toproduce a halo thiadiazole alkylating agent. In sequence XXIII, thisalkylating agent is then reacted with a metal alkyl, or with a compoundhaving an alkoxy or alkylthio anion, followed by quaternization andsodium borohydride reduction to produce a thiadiazole of structure (ii).In accordance with sequence XXIV, the halo thiadiazole alkylating agentof step XXI is reacted (step XXIV) with a metal alkyl, or, for example,with an alkoxy or alkylthio anion followed by catalytic reduction and,alkylation to form thiadiazole compounds of structure (i) and (iii).

Compounds (i) and (iii) of sequence XXIV can also be converted to (i)structures, when Y is NR', R' is CO(O)R or trityl, by deprotection withTFA (trifluoroacetic acid).

As indicated above, the aminonitrile compound resulting from theStrecker synthesis (sequence XIX) can also be formed into compound (i)by reaction sequences XX, XXII and XXV. In sequence XX the aminonitrileis hydrolized, with the product then being subjected to catalyticreduction and alkylation to produce a protected pyrimidine amide. Thisprotected pyrimidine is then subjected to cyclization (XXII) employingsulfur monochloride, or thionylaniline, to produce a hydroxy thiadiazolesubstituent on a 1,4,5,6-tetrahydropyrimidine nucleus. Finally,compounds of formula (i) are formed when R' is C(O)OR or trityl in theproduct of step XXII in accordance with step XXV by alkylation anddeprotection.

Using a cyano methyl pyrimidine compound, compounds of structure (ii)can be formed by reaction sequences XXVII, XXVIII and XXX. From aproperly substituted cyano methyl pyridine or pyrimidine compound,structures (i) and (iii) can be formed by reaction sequences XXVII,XXVIII and XXXI. Compounds of structure (i) can also be formed byreaction sequence XXVII, XXXVII, XXIX and XXXII.

In reaction sequence XXVII, the substituted pyridine or pyrimidinecompound is subjected to a base catalyzed reaction with a methylnitriteto form a cyano oxime. The cyano oxime is then reacted (sequence XXVIII)with hydroxylamine and then cyclized using phosphorous pentachloride andthe cyclized product is then subjected to diazotization and thenchlorination to produce an alkylating halooxadiazole substituted halopyridine or pyrimidine compound. In reaction sequence XXX, thepyrimidine compound is reacted with a metal alkyl or with an MX'Rcompound and then subjected to quaternization followed by sodiumborohydride reduction to produce compounds of structure (ii).

The step XXVIII compound is used to form compounds of structure (i) or(iii) in accordance with reaction sequence XXXI by first of all reactingwith an R" M compound followed by catalytic reduction and thenalkylation when Y is N. It can be observed in the reaction sequencesthat by dealkylation, or deprotection, compounds produced in accordancewith reaction sequence XXXI, when Y is NR' and R' is C(O)OR or trityl,can be converted to compounds of structure (i) as illustrated inreaction sequence XXXIII.

The cyano oxime of reaction sequence XXVII can also be converted,through reaction sequences XXXVII, XXIX and XXXII, to compounds ofstructure (i). In reaction sequence XXXVII, the cyano oxime is reactedwith hydroxylamine and then subjected to catalytic reduction followed byalkylation to form the properly protected amino oxime. The lattermaterial, in accordance with reaction sequence XXIX, is subjected tocyclization, using phosphorous pentachloride, and then subjected todiazotization and chlorination to form an alkylated, chlorooxadiazolesubstituted, tetrahydropyrimidine structure which is then employed as analkylating agent in reaction sequence step XXXII to react with an R" Mcompound followed by deprotection with TFA to produce structure (i).

The symbols used above, e.g. R", M, R, etc., to describe the variousreaction sequences are those set forth below in the respective reactionsequence flow diagrams. In the above description, it will be apparentthat alkylation, along with protection, is provided when required forthe selected properly substituted product. ##STR3##

Those skilled in the art with the foregoing reaction sequences willroutinely select the starting materials needed to produce the compounds,or their pharmaceutically acceptable salts as contemplated by thepresent invention.

The following preparative examples are further provided to enable andaid those skilled in the art to practice the invention. These examplesare representative synthesis techniques, but they are only illustrativeof the present invention and are not to be read as limiting the scope ofthe invention. The examples include not only the general synthesismethod for producing compounds, and their pharmaceutically acceptablesalts, in accordance with the invention, but also present representativestarting material preparation techniques.

EXAMPLES Example 1 5-Methoxycarbonylpyrimidine

1) Crude pyrimidine-5-carboxylic acid (1.24 g, 10 mmol) was dissolved in100 ml THF (dry), 3 ml water, and cooled to 0° C. in the reaction vesselof a Mini-Diazald® apparatus (Aldrich Chemical). Diazald® (3 g, 14 mmol)dissolved in ether (27.5 ml) was added dropwise over 15 minutes to KOH(3 g) in ethanol/water (11 ml) at 65° C. to generate diazomethane. Ether(20 ml) was added dropwise, after the Diazald® solution, to co-distillthe remaining diazomethane into the reaction flask. The reaction wasallowed to stir 3 hours until nitrogen evolution had stopped, and excessdiazomethane was then destroyed by adding acetic acid. The solvents wereevaporated in vacuo, the residue taken up in 50 ml water, basified to pH9 (NaCO₃), and extracted with chloroform (3×100 ml). After drying(MgSO₄), filtering, and evaporating the solvent in vacuo, 1.26 g (91%)crude crystals were obtained. Recrystallization from chloroform/hexanegave 606 mg (44%) light yellow crystals mp 81.6°-86.6° C. Microanalysiscalc.: C52.17, H 4.38, N 20.29; found: C 51.95, H 4.31, N 19.96. 400 MHznmr indicated product.

2) Crude pyrimidine-5-carboxylic acid (2.4 g, 19.38 mmol) was suspendedin 100 ml methanol in a round bottom flask fitted with a refluxcondenser, drying tube, and a dropping funnel, and 2.8 ml thionylchloride was added dropwise with stirring. The suspension was stirredand refluxed overnight; then cooled to room temperature and the solventsevaporated in vacuo. Ice cold water (50 ml) was added, basified to pH 8(sat. NaHCO₃), and extracted with chloroform (3×50 ml). The organicswere dried (MgSO₄), filtered and evaporated in vacuo to yield 2.07 gcrude yellow crystals (77%).

1,4,5,6-Tetrahydro-5-methoxycarbonylpyrimidine Hydrobromide

5-Methoxycarbonylpyrimidine (1.381 g, 10 mmol) in 143 ml 0.07158M HBrwas hydrogenated at 26 psig over 600 mg Pd-on-carbon 10% in a Parrhydrogenator for three hours. The suspension was filtered and the filterrinsed twice with hot water (10 ml). The filtrate was evaporated invacuo to give 1.86 g yellow oil (83%). The oil was crystallized fromanhydrous ethanol/THF, and the hygroscopic crystals collected bydecanting the solvents under a stream of nitrogen. Excess solvents wereremoved under vacuum in a drying pistol to yield 1.01 g (45%) whitecrystals mp 149°-153° C. (with the evolution of gas). Microanalysiscalc.: C32.3, H 4.97, N 12.56; found: C 32.12, H 5.15, N 12.34. MHz nmrindicated product.

Example 2 1,4,5,6-Tetrahydropyrimidine-5-carboxylic Acid Hydrochloride

Pyrimidine-5-carboxylic acid (5.0 g, 40 mmol) was suspended in a mixtureof 150 ml water and concentrated hydrochloric acid (4.0 g, 40.5 mmol).The mixture was hydrogenated at 26 psig over 1.0 g Pd-on-carbon 10% in aParr hydrogenator for 3h. The suspension was filtered and the filterrinsed twice with hot water (20 ml). The filtrate was evaporated invacuo to give 6.11 g yellow oil (92%). The oil was crystallized fromanhydrous methanol/tetrahydrofuran (THF) to give 5.77 g (87%) whitecrystals in two crops. 300 MHz nmr indicated product.

1,4,5,6-Tetrahydro-5-ethoxycarbonylpyrimidine Hydrochloride

1,4,5,6-Tetrahydropyrimidine-5-carboxylic acid hydrochloride (1.5 g,9.12 mmol) was dissolved in absolute ethanol (40 ml) by heating. Thethionyl chloride (1.1 g, 9.16 mmol) was added dropwise with stirring.The resulting solution was refluxed 20h and then evaporated to drynessin vacuo. The residue was taken up in absolute methanol (5 ml) and dryTHF (10 ml) was added to induce crystallization, giving 1.1 g (63%)product as white crystals, mp 125°-127° C. 300 MHz nmr confirmed theproduct. Microanalysis calc.: C 43.64, H 6.75, N 14.55; found: C, 43.43,H 6.58, N 14.40.

Example 3 n-Propyl 1,4,5,6-Tetrahydropyrimidine-5-carboxylateHydrochloride

1,4,5,6-Tetrahydropyrimidine-5-carboxylic acid hydrochloride (1.5 g, 9.1mmol) was dissolved in 1-propanol (30 ml). To the mixture was addedthionyl chloride (1.1 g, 9.1 mmol) and the solution was refluxed for22h. The solvent was evaporated in vacuo to dryness. The residue wascrystallized from methanol/THF to give 1.06 g (56%) of white crystals,mp 128°-130° C. 300 MHz nmr indicated product. Microanalysis calc.: C46.49, H 7.26, N 13.56, found: C 46.21, H 6.96, N 17.41.

Example 4 Isopropyl 1,4,5,6-Tetrahydropyrimidine-5-carboxylateHydrochloride

1,4,5,6-Tetrahydropyrimidine-5-carboxylic acid hydrochloride (1.0 g,6.08 mmol) was suspended in 2-propanol (50 ml) and thionyl chloride(0.76 g, 6.39 mmol) was added dropwise. The resulting mixture wasrefluxed 24h. The pink solution was treated with charcoal and thenreduced in volume to 15 ml by evaporating unreacted alcohol. By allowingthe solution to stand overnight, white crystals (1.08 g, 84%) wereobtained in three crops, mp 170° C. 300 MHz nmr confirmed product.Microanalysis calc.: C 46.49, H 7.26, N 13.56, found: C 46.49, H 7.25, N13.64.

Example 5 Benzyl 1,4,5,6-Tetrahydropyrimidine-5-carboxylateHydrochloride

1,4,5,6-Tetrahydropyrimidine-5-carboxylic acid hydrochloride (1.0 g, 6.1mmol) was suspended in dry benzyl alcohol (20 ml). To the mixture wasadded thionyl chloride (0.76 g, 6.39 mmol) and the resulting mixture washeated in an oil bath at 80° C. for 24h. The clear solution was pouredto anhydrous ethyl ether (100 ml) to induce precipitation. The whitesolids were collected and crystallized from methanol/THF to give 1.18 g(76%) of product (mp 113°-114° C.). 300 MHz nmr indicated the product.Microanalysis calc.: C 56.58, H 5.89, N 11.00; found: C 56.34, H 6.03, N11.19.

Example 6 Propynxl 1,4,5,6-Tetrahydropyrimidine-5-carboxylateHydrochloride

1,4,5,6-Tetrahydropyrimidine-5-carboxylic acid hydrochloride (2.22 g,13.5 mmol) was suspended in oxalyl chloride (30 ml). The mixture wasrefluxed for 6h with stirring and then unreacted oxalyl chloride wasevaporated to dryness. To the residue was added propargyl alcohol (20ml) and the resulting mixture was stirred for 10h at room temperature.The mixture was evaporated in vacuo to dryness. The residue wasrecrystallized from methanol/THF to give white crystals--400 mg (14%),mp 127°-129° C. Microanalysis calc.: C 45.40, H 5.67, N 13.23; found: C45.55, H 5.70, N 13.18.

Example 7 1,4,5,6-Tetrahydro-5-methoxycarbonylpyrimidine Hydrochloride

1,4,5,6-Tetrahydropyrimidine-5-carboxylic acid hydrochloride (6.34 g,38.5 mmol) was dissolved in anhydrous methanol (200 ml) with stirring,and thionyl chloride (2.74 ml, 38.5 mmol) was added dropwise. Theresulting solution was refluxed with stirring for 18 hours, thenevaporated in vacuo to white solids. The crude product wasrecrystallized from anhydrous methanol to yield 4.12 g (60%) whitecrystals, mp 160°-164° C. Calculated: C 40.34, H 6.21, N 15.69; found: C40.17, H 6.41, N 15.73.

1-Methyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine

1,4,5,6-Tetrahydro-5-methoxycarbonylpyrimidine hydrochloride (300 mg,1.35 mmol) and NaH (60% in mineral oil 107 mg, 1.35 mmol) were suspendedin anhydrous DMF (5 ml) in an oven dried round bottom flask withstirring under nitrogen. After stirring 15 minutes CH₃ I 84 μl, 1.35mmol) was added via syringe and stirring continued 3 hours at roomtemperature. The solvents were evaporated in vacuo and the residuetriturated with chloroform. The resulting suspension was filtered andevaporated in vacuo. Chromatography (silica, chloroform/methanol, 9:1)gave 160 mg (76%) crystals mp 93°-95° C. identified by 300 MHz nmr; msm/z=156.

Example 81-Methyl-1,4,5,6-Tetrahydro-5-(3-methyl-1,2,4-oxadiazol-5-yl)pyrimidine

Sodium hydride (60% dispersion in mineral oil 112 mg, 2.8 mmol) andacetamidoxime (207 mg, 2.8 mmol) are suspended in dry THF (16 ml) in anoven dried round bottom flask under nitrogen with stirring at 0° C.After 10 minutes the grey suspension is refluxed for 30 minutes giving awhite suspension.1-Methyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (593 mg, 2.8mmol) dissolved in dry THF (4 ml) and anhydrous ethanol (1 ml) is addedvia syringe and reflux continued 15 hours. The suspension is evaporatedin vacuo to a yellow gum and chromatographed (silica,chloroform/methanol, 9:1) to yield 24 mg (rf=0.07, 4%) solids identifiedby 300 MHz nmr and ms m/z=180.

Example 91-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine

1,4,5,6-Tetrahydro-5-methoxycarbonylpyrimidine hydrochloride (1.49 g,8.3 mmol) , 1,8 diazabicyclo [5.4.0] undec-7ene, (hereinafterdiazabicycloundecene and/or DBU), (2.5 mL, 16.6 mmol), andtritylchloride (2.32 g, 8.3 mmol) were suspended in anhydrous DMF (20ml) with stirring under nitrogen at room temperature. After 18 hoursstirring the suspension was evaporated in vacuo and the residuechromatographed (silica, chloroform/methanol, 9:1) to yield 2.28 g(rf=0.15, 71%)white crystalline solid identified by 300 MHz nmr and msm/z=384.

1-Triphenylmethyl-1,4,5,6-tetrahydro-5-(3-methyl-1,2,4-oxadiazol-5-yl)pyrimidine

Sodium hydride (60% dispersion in mineral oil 26 mg, 0.65 mmol) andacetamidoxime (48 mg, 0.65 mmol) were suspended in dry THF (4 ml) in anoven dried round bottom flask with stirring under nitrogen at 0° C.After 15 minutes stirring the ice bath was removed and the greysuspension refluxed 45 minutes to give a white suspension.1-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (250mg, 0.65 mmol) was added dissolved in dry THF (3 ml) and refluxcontinued 18 hours. The solvents were evaporated in vacuo and theresidue taken up in water (10 ml). The aqueous suspension was extractedexhaustively with chloroform and the organics dried over MgSO₄. Afterevaporation the organic residue was chromatographed (silica,chloroform/methanol, 9:1) to yield 93 mg (rf=0.26, 35%) white crystals,mp 72°-74° C. identified by 300 MHz nmr and ms m/z=408. Calculated: C76.44, H 5.9, N 13.7; found: C 76.27, H 6.06, N 13.59.

1,4,5,6-Tetrahydro-5-(3-methyl-1,2,4-oxadiazol-5-yl)pyrimidinetrifluoroacetate

1-Triphenylmethyl-1,4,5,6-tetrahydro-5-(3-methyl-1,2,4-oxadiazol-5-yl)pyrimidine(254 mg, 0.6 mmol) is dissolved in trifluoroacetic acid (TFA) (1 mL)with stirring at room temperature for 24 hours. The dark solution isthen evaporated in vacuo, and the residue recrystallized frommethanol/ether to yield 105 mg (62%) white crystals, mp 120°-122° C.identified by 300 MHz nmr. Calculated: C 38.57, H 3.96, N 19.99; found:C 38.72, H 4.09, N 19.78.

Example 10 5-Acetoxy-1,4,5,6-tetrahydropyrimidine HCl

5-Hydroxy-1,4,5,6-tetrahydropyrimidine (JOC, 1966, 31, 3838; 1 g, 10mmol) was dissolved in glacial acetic acid (25 ml) with stirring, andthionylchloride (0.73 ml, 10 mmol) was added dropwise. The resultingsolution was refluxed 19 hours, then evaporated to dryness in vacuo. Theresidue was taken up in water (5 ml), the pH adjusted to 12 (sat. Na₂CO₃), and extracted with chloroform. The chloroform was dried (MgSO₄)and evaporated in vacuo to 440 mg (25%) product as a clear oilidentified by 400 MHz nmr. The oil was converted to its HCl salt inanhydrous ethanol with addition of IM HCl in ether. After evaporation ofsolvents the resulting crude HCl salt was recrystallized from ethanol toyield 128 mg (7%) white crystals, mp 287°-289° C. 400 MHz nmr and irconfirmed product. Calculated: C 40.34, H 6.2, N 15.69; found: C 40.45,H 6.19, N 15.53.

Example 11 1-Methyl-5-methoxycarbonylpyrimidinium iodide

5-Methoxycarbonylpyrimidine (597 mg, 4.3 mmol) and methyliodide (1.6 ml,26 mmol) were dissolved in acetonitrile (20 ml) in a stoppered flask andstirred at room temperature. After five days diethyl ether was added toprecipitate red crystalline product 314 mg (26%), mp 167°-170° C. witheffervescence. Calculated: C 30.02, H 3.24, N 10.00; found: C 29.88, H3.30, N 10.07.

1-Methyl-5-methoxycarbonyl-1,2,3,6-tetrahydropyrimidine HCl

1-Methyl-5-methoxycarbonylpyrimidinium iodide (2.8 g, 7.2 mmol) wasdissolved in anhydrous methanol (50 ml) and NaBH₄ (270 mg, 7.2 mmol) wasadded at room temperature with stirring. After stirring overnight thesolvents were removed in vacuo. The residue was taken up in water (50ml), extracted with chloroform and the extracts dried (MgSO₄). Theresidue obtained on removal of solvents was chromatographed (silica,chloroform/methanol, 9:1) to give the product as a yellow resin rf=0.35185 mg (16%) identified by 400 MHz nmr. The hydrochloride salt wasobtained by addition of 1M HCl in ether to an ethanol solution of theresin, evaporation of solvents and recrystallization (ethanol/ether) toyield 35 mg (15%) yellow crystals mp 160°-162° C. Calculated: C 43.64, H6.80, N 14.54; found: C 43.55, H 6.65, N 14.40.

Example 12 5-(1,3-dioxolan-2-yl)pyrimidine

Pyrimidine-5-carboxaldehyde (1.017 g, 9.41 mmol) was dissolved inbenzene (25 ml) with heat in a 100 ml round bottomed flask fitted with acondenser, drying tube and a Dean-stark trap. p-Toluene sulfonic acid(0.179 g, 0.941 mmol) and ethylene glycol (1.1 ml, 18.82 mmol) wereadded and the mixture refluxed overnight. After cooling to roomtemperature the excess benzene was evaporated in vacuo. Saturated sodiumcarbonate (10 ml) was added and extracted with chloroform (7×10 ml). Thechloroform extract was dried over magnesium sulfate, filtered and thesolvent evaporated in vacuo to give 1.1611 g (81%) yellow oil. TLC onsilica gel using chloroform/methanol (9:1) indicated the product andsome starting material. Column chromatographic separation on silica geland the same solvent system gave 0.911 g (64%) yellow oil rf=0.78 whichwas freeze-dried in a lyophilizer to obtain crystals. 300 MHz nmrindicated product. Microanalysis calc.: C55.25, H 5.30, N 18.42; found:C 55.12, H 5.22, N 18.24.

1-Methyl-5-(1,3-dioxolan-2-yl)pyrimidinium iodide

5-(1,3-dioxolan-2-yl)pyrimidine (0.573 g, 3.77 mmol) and acetonitrile (3ml) were stirred under dry nitrogen in a bomb tube with rubber seal.Methyl iodide (0.7 ml, 11.30 mmol) was added, the bomb properly sealedand stirring continued at room temperature overnight. This resulted in ayellow suspension which was vacuum-filtered to obtain yellow powderycrystals. The powder was put in drying pistol to give 0.881 g (84%)yellow crystals. Recrystallization from ethanol gave fine crystals mp188°-190° C. 300 MHz nmr in dimethyl sulfoxide (DMSO) indicated product.Microanalysis calc: C 32.67, H 3.77, N 9.53; found: C 32.66, H 3.81, N9.42.

1-Methyl-1,2,3,6-tetrahydro-5-(1,3-dioxolan-2-yl)pyrimidineHydrochloride

1-Methyl-5-(1,3-dioxolan-2-yl)pyrimidinium iodide (0.881 g, 3mmol) andNaBH₄ (113 mg, 3 mmol) are stirred in methanol (20 mL) under drynitrogen in around bottom flask with a rubber septum. This results in ayellow solution which is vacuum-evaporated, taken up in water, andextracted with chloroform. The residue obtained on evaporation of thechloroform is chromatographed (silica, chloroform/methanol, 9:1) toyield the free base, which is converted to its hydrochloride salt.Recrystallization from ethanol/ether gives fine white crystals (500 mg,80%) identified by 300 MHz nmr.

Example 13 5-(1,3-oxathiolan-2-yl)pyrimidine

Pyrimidine-5-carboxaldehyde (1 g, 9.25 mmol), p-toluene sulfonic acid(0.176 g, 0.95 mmol) and 2-mercaptoethanol (0.65 ml, 9.25 mmol) were allput in a 50 ml round bottomed flask, fitted with a condenser, dryingtube and a Dean-stark trap. Toluene (30 ml) was added and the mixturerefluxed with stirring overnight, cooled to room temperature and excesstoluene evaporated in vacuo. Saturated sodium carbonate 10 ml was addedand extracted with chloroform (7×10 ml). The extract was dried overMgSO₄, filtered and the solvent evaporated in vacuo to 1.73 g (115%)crude yellow oil. TLC (silica; chloroform/methanol 9.8:0.2) indicatedthe product and some impurities.

Column chromatographic separation on silica gel using the same solventsystem gave 0.780 g (52%) yellow oil. 300 MHz nmr indicated purecompound. Microanalysis calc.: C 49.98, H 4.79, N 16.66, S 19.06; found:C 50.02, H 5.04, N 16.48, S 18.91.

1-Methyl-5-(1,3-oxathiolan, 2-yl)pyrimidinium Iodide

5-(1,3-oxathiolan-2-yl)pyrimidine (0.780 g, 5.1 mmol) and acetonitrile(3 ml) are stirred under dry nitrogen in a bomb tube with rubber seal.Methyl iodide (0.7 ml, 11.30 mmol) is added, the bomb properly sealed,and stirring continued at room temperature overnight. This results in ayellow suspension which is vacuum-filtered to obtain yellow powderycrystals. The powder is put in a drying pistol to give 1.32 g (84%)yellow crystals. Recrystallization from ethanol gives fine crystalsidentified by 300 MHz nmr.

1-Methyl-1,2,3,6-tetrahydro-5-(1,3-oxathiolan-2-yl)pyrimidineHydrochloride

1-Methyl-5-(1,3-dioxolan-2-yl) pyrimidinium iodide (1.32 g, 4.3 mmol)and NaBH₄ (161 mg, 4.3 mmol) are stirred in methanol (20 mL) under drynitrogen in a round bottom flask fitted with a rubber septum. Thisresults in a yellow solution which is vacuum-evaporated, taken up inwater, and extracted with chloroform. The residue obtained onevaporation of the chloroform is chromatographed (silica,chloroform/methanol, 9:1) to yield the free base, which is converted toits hydrochloride salt. Recrystallization from ethanol/ether gives finewhite crystals (772 mg, 80%) identified by 300 MHz nmr.

Example 14 2-Amino-5-methoxycarbonylpyridine

6-Aminonicotinic acid (1.06 g, 7.7 mmol) was suspended with stirring inanhydrous methanol (50 ml), and thionyl chloride (0.55 ml, 7.7 mmol) wasadded dropwise. The suspension was refluxed to a clear solution over 15hours. The solvent was evaporated in vacuo and the residue taken up inwater (20 ml). The solution was raised to pH 9 (sat. Na₂ CO₃), extractedwith chloroform, and dried over MgSO₄. Evaporation of the chloroformgave 1.23 g (100%) product as white crystals identified by 400 MHz nmrand ir 1694 cm⁻¹.

2-Amino-3,4,5,6-tetrahydropyridine-5-carboxylic acid HCL

2-Amino-5-methoxycarbonylpyridine (0.912 g, 6.6 mmol) was dissolved in90% ethanol (137 ml) and conc. HCl (3.5 ml, 40 mmol) was added. Thesolution was hydrogenated over PtO₂ (200 mg) in a Parr shaker apparatusat room temperature and 29 psig for 2 hours. Filtration and evaporationgave 1.05 g (89%) crude white crystals identified as the product by 400MHz nmr and ir 3350, 3011, 1714 cm⁻¹.

2-Amino-5-methoxycarbonyl-3,4,5,6-tetrahydropyridine HCl

2-Amino-3,4,5,6-tetrahydropyridine-5-carboxylic acid HCl (1 g, 5.6 mmol)was suspended in anhydrous methanol (100 ml), and thionyl chloride (0.5ml, 7 mmol) was added dropwise with stirring at room temperature. Theresulting solution was refluxed overnight and then evaporated to drynessin vacuo. The resulting crude white solid was recrystallized frommethanol/ether to give white crystals 589 mg (54%) mp 177°-179° C.,identified as product by 300 MHz nmr and ir 1733 cm⁻¹. Calculated: C43.64, H 6.8, N 14.55; found: C 43.63, H 6.75, N 14.56.

Example 15 2-Amino-3,4,5,6-Tetrahydropyridine-3-Carboxylic acid HCl

2-Aminonicotinic acid (0.912 g, 6.6 mmol) was dissolved in 90% methanol(137 ml) and conc. HCl (3.5 ml, 40 mmol) was added. The solution washydrogenated over PtO₂ (200 mg) in a Parr shaker apparatus at roomtemperature and 29 psig for 2 hours. Filtration and evaporation gave1.22 g (100%) oily product identified by ir 3300-2500, 1724 cm⁻¹.

2-Amino-3-methoxycarbonyl-3,4,5,6-tetrahydropyridine HCl

2-Amino-3,4,5,6-tetrahydropyridine-3-carboxylic acid HCl (1.2 g, 6.6mmol) was suspended in anhydrous methanol (100 ml), and thionyl chloride(0.5 ml, 7 mmol) was added dropwise with stirring at room temperature.The resulting solution was refluxed overnight and then evaporated todryness in vacuo. The resulting crude white solid was recrystallizedfrom methanol/ether to give white crystals 613 mg (46%) mp 138°-139° C.,identified as product by 300MHz nmr and ir 1737 cm⁻¹. Calculated: C43.64, H 6.8, N 14.55; found: C 43.75, H 6.87, N 14.57.

Example 16 2-Amino-3,4,5,6-tetrahydropyridine-4-carboxylic acid HCL

2-Aminopyridine-4-carboxnylic acid (Farinaco. Ed. Sci. 1958, 13,485;1.38 g, 10 mmol) was dissolved in 90% methanol (210 ml) and conc.HCl(4.9 ml, 60 mmol) was added. The solution was hydrogenated over PtO₂(200 mg) in a Parr shaker apparatus at room temperature and 29 psig for2 hours. Filtration and evaporation gave 1.57 g (88%) crude whitecrystals identified as the product by 300 MHz nmr and ir 1728 cm⁻¹.

2-Amino-4-methoxycarbonyl-3,4,5,6-tetrahydropyridine HCL

2-Amino-3,4,5,6-tetrahydropyridine-4-carboxylic acid HCl (1.54 g, 8.6mmol) was suspended in anhydrous methanol (100 ml), and thionyl chloride(0.6 ml, 8.6 mmol) was added dropwise with stirring at room temperature.The resulting solution was refluxed overnight and then evaporated todryness in vacuo. The resulting crude white solid was recrystallizedfrom methanol/ether to give white crystals 452 mg (27%) mp 180°-181° C.,identified as product by 300 MHz nmr and ir 1733 cm⁻¹. Calculated: C43.64, H 6.8, N 14.55; found: C 43.42, H 6.65, N 14.66.

Example 17 2-Amino-3,4,5,6-tetrahydropyridine-6-carboxylic acid HCl

2-Aminopyridine-6-carboxylic acid (Farinaco. Ed. Sci. 1959, 14, 594;2.01 g, 14.5 mmol) was dissolved in 90% methanol (200 ml) and conc. HCl(7.2 ml, 87.4 mmol) was added. The solution was hydrogenated over PtO₂(340 mg) in a Parr shaker apparatus at room temperature and 29 psig for2 hours. Filtration and evaporation gave 2.08 g (80%) crude whitecrystals identified as the product by 300 MHz nmr and ir 1724 cm⁻¹.

2-Amino-6-methoxycarbonyl-3,4,5,6-tetrahydropyridine HCL

2-Amino-3,4,5,6-tetrahydropyridine-6-carboxylic acid HCl (1.99 g, 11.1mmol) was suspended in anhydrous methanol (100 ml), and thionyl chloride(0.8 ml, 11.1 mmol) was added dropwise with stirring at roomtemperature. The resulting solution was refluxed overnight and thenevaporated to dryness in vacuo. The resulting crude white solid wasrecrystallized from ethanol to give white crystals 656 mg (31%) mp132°-134° C., identified as product by 300 MHz nmr and ir 1753 cm⁻¹.Calculated: C 43.64, H 6.8, N 14.55; found: C 43.80, H 6.81, N 14.46.

Example 18 2-Trifluoromethyl-5-hydroxy-1,4,5,6-tetrahydropyrimidine

1,3-Diamino-2-hydroxypropane (10 g, 111 mmol) and ethyltrifluoroacetate(13.5 ml, 114 mmol) were dissolved in xylene (85 ml) and refluxedovernight in a Dean-Stark apparatus. The solvents were evaporated invacuo to give a dark viscous oil 21 g identified by 300 MHz nmr asproduct.

5-Acetoxy-2-trifluoromethyl-1,4,5,6-tetrahydropyrimidine HCl

2-Trifluoromethyl-5-hydroxy-1,4,5,6-tetrahydropyrimidine (111 mmol) wasdissolved in glacial acetic acid (100 ml) with stirring, and thionylchloride (8.1 ml, 111 mmol) was added dropwise. The resulting solutionwas refluxed 19 hours, then evaporated to dryness in vacuo. The residuewas taken up in water (50 ml), the pH adjusted to 9 (sat. Na₂ CO₃), andextracted with chloroform. The chloroform was dried (MgSO₄) andevaporated in vacuo to 2 g (90%) crude product as a clear red oilidentified by 400 MHz nmr. The oil was converted to its HCl salt inanhydrous ethanol with addition of 1M HCl in ether. Unreacted startingmaterial, as the hydrochloride, was collected and the mother liquorevaporated, treated with aqueous base and extracted with chloroformagain. Chromatography (silica 60, chloroform/methanol) gave 440 mg crudeproduct as an oil that was again converted to its hydrochloride salt inethanol. After evaporation of solvents the crude HCl salt wasrecrystallized from ethanol/ether to yield 242 mg (0.8%) tan crystals,mp 197°-199° C. 400 MHz nmr confirmed the product calculated: C 34.09, H4.09, N 11.36; found: C 34.13, H 4.14, N 11.50.

Example 19 2-methyl-5 acetoxy-1,4,5,6-tetrahydropyrimidine

2-Methyl-5-hydroxy-1,4,5,6-tetrahydropyrimidine (JOC 1966, 31, 3838; 1.5g, 13.3 mmol) was dissolved in glacial acetic acid (100 ml) withstirring, and thionyl chloride (1 ml, 13.1 mmol ) was added dropwise.The resulting solution was refluxed 19 hours, then evaporated to drynessin vacuo. The residue was taken up in water (5 ml), the pH adjusted to 9(sat. Na₂ CO₃), extracted with chloroform and the organics discarded.The aqueous layer was then adjusted to pH 12 (sat. NaOH) and extractedwith chloroform. The chloroform was dried (MgSO₄) and evaporated invacuo to 575 mg (28%) white crystals, mp 141°-146° C. 400 MHz nmrconfirmed the product calculated: C 53.82, H 7.75, N 17.94; found: C53.9, H 7.73, N 17.77.

Example 201-Methyl-3-triphenylmethyl-5(3-methyl-1,2,4-oxadiazol-5-yl)-1,4,5,6-tetrahydropyrimidiniumIodide

Methyliodide (38 μl, 0.6 mmol) was added to a stirred solution of1-triphenylmethyl-5(3-methyl-1,2,4-oxadiazol-5-yl)-1,4,5,6-tetrahydropyrimidine (250 mg, 0.6 mmol) in chloroform (1 ml),in a round bottom flask with a septum, at room temperature. After 12hours stirring the solvents were evaporated in vacuo giving 330 mg(100%) crude white crystals identified by 300 MHz nmr.

1-Methyl-5(3-methyl-1,2,4-oxadiazol-5-yl)-1,4,5,6-tetrahydropyrimidineHCl

1-Methyl-3-triphenylmethyl-5(3-methyl-1,2,4-oxadiazol-5-yl)-1,4,5,6-tetrahydropyrimidiniumIodide (330 mg, 0.6 mmol) was dissolved in TFA (1 mL) with stirring in astoppered round bottom flask at room temperature. After 18 hoursstirring the excess TFA was evaporated in vacuo, and the dark residuetriturated with ether. The ether was decanted leaving an oily residuethat was taken up in ice cold sat. Na₂ CO₃ and then extracted withchloroform. After drying and evaporation the chloroform fraction gavethe free base which was converted to its HCl salt and recrystallized(methanol/ether) to yellow crystals 15 mg (12%) identified by 300 MHznmr and ms m/z=180.

Example 211-Methyl-3-triphenylmethyl-5-methoxycarbonyl-1,4,5,6-tetrahydropyrimidiniumiodide

Methyliodide (47 μl, 0.6 mmol) is added to a stirred solution of1-triphenylmethyl-5-methoxycarbonyl-1,4,5,6-tetrahydropyrimidine (288mg, 0.75 mmol) in chloroform (5 ml), in a round bottom flask with aseptum, at room temperature. After 12 hours stirring the solvents areevaporated in vacuo giving 395 mg (100%) white crystals identified by300 MHz nmr.

1-Methyl-5-methoxycarbonyl-1,4,5,6-tetrahydropyrimidine

1-Methyl-3-triphenylmethyl-5-methoxycarbonyl-1,4,5,6-tetrahydropyrimidiniumiodide (395 mg, 0.75 mmol) is dissolved in TFA (1 ml) with stirring in astoppered round bottom flask at room temperature. After 18 hoursstirring the excess TFA is evaporated in vacuo, and the dark residuetriturated with ether. The ether is decanted leaving an oily residuethat is taken up in ice cold sat. Na₂ CO₃ and then extracted withchloroform. After drying and evaporation the chloroform fraction gavethe free base which is recrystallized (chloroform/hexane) to yellowcrystals 88 mg (74%) identified by 300 MHz nmr, ms m/z=156.

Example 22 Amino(pyrimidin-5-yl)acetonitrile

Potassium cyanide (651 mg, 10 mmol) and ammonium chloride (588 mg, 11mmol) are dissolved in water (2.6 mL) with stirring.Pyrimidine-5-carboxaldehyde (1.08 g, 10 mmol) in methanol (2.6 mL) isadded to the clear solution rapidly, giving first a yellow, then a darkred solution, and mildly exothermic reaction. The water is evaporatedafter three hours stirring, and the reddish residue is chromatographed(silica, chloroform/methanol) to give a yellow solid 1.1 g (82%)identified as product ms m/z=134.

Amino(pyrimidin-5-yl)-acetamide

Amino (pyrimidin-5-yl)acetonitrile (1.1 g, 8.2 mmol) is hydrolyzed byrefluxing in a small volume of dilute HCl for 1 hour. The pH is raisedto 10 by addition of saturated sodium carbonate and the mixture thenextracted with chloroform. Evaporation of the chloroform andchromatography (silica, chloroform/methanol) gives product as a yellowsolid 950 mg (81%) ms m/z=142.

Amino(1,4,5,6-tetrahydropyrimidine-5-yl)acetamide dihydrochloride

Amino(pyrimidin-5-yl)acetamide (950 mg, 6.7 mmol) is suspended in amixture of 50 ml water and concentrated hydrochloric acid (13.3 mmol).The mixture is hydrogenated at 26 psig over 300 mg Pd-on-carbon 10% in aParr hydrogenator for 3h. Then the suspension is filtered and the filterrinsed twice with hot water (20 ml). The filtrate can be evaporated invacuo to give 1.41 g yellow oil (92%). The oil is crystallized fromanhydrous methanol/THF to give 1.33 g (87%) white crystals, identifiedby 300 MHz nmr.

Amino(1-triphenylmethyl-1,4,5,6-tetrahydropyrimidin-5-yl)acetamide

Amino(1,4,5,6-tetrahydropyrimidine-5-yl)acetamide dihydrochloride (1.33g, 5.8 mmol), diazabicycloundecene (DBU, 2.6 ml, 17.4 mmol), andtritylchloride (1.61 g, 5.8 mmol) are dissolved in anhydrous DMF (20 ml)with stirring under nitrogen at room temperature. After 18 hoursstirring the suspension is evaporated in vacuo, and the residuechromatographed (silica, chloroform/methanol, 9:1) to yield 1.64 g (71%)white crystalline solid, identified by 300 MHz nmr and ms m/z=398.

1-Triphenylmethyl-5(3-hydroxy-1,2,5-thiadiazol-4-yl)-1,4,5,6-tetrahydropyrimidine

N-Thionylaniline (2.6 mL, 23.2 mmol) is added toamino(1-triphenylmethyl-1,4,5,6-tetrahydropyrimidin-5-yl)acetamide (1.64g, 4.1 mmol) suspended in pyridine (25 ml). After heating at 90° C. for48 hours the pyridine is evaporated, and the black residue partitionedbetween chloroform and water. The aqueous layer is lowered to pH 5 (HCl)and chromatographed (Dowex-50W, 0.5N ammonium hydroxide) to yield theproduct as a brown solid 1.05 g (61%) that can be further purified bychromatography (silica, methanol) and converted to a white crystallinehydrochloride salt, ms m/z=426.

1-Triphenylmethyl-5(3(1-n-heptanoxy)-1,2,5-thiadiazol-4-yl)-1,4,5,6-tetrahydropyrimidineHCl

1-Triphenylmethyl-5(3-hydroxy-1,2,5-thiadiazol-4-yl)-1,4,5,6-tetrahydropyrimidine(1.05 g, 2.46 mmol) and NaH (60 mg, 2.46 mmol) are suspended in DMF (20ml), and 1-iodoheptane (0.4 ml, 2.46 mmol) is added via syringe at roomtemperature. After stirring 5 minutes the reaction can be heated to 60°C. for 18 hours. DMF is then evaporated in vacuo, the residue dissolvedin chloroform, and washed with water and saturated brine. Evaporation ofthe chloroform and chromatography (silica, chloroform/methanol) givesthe free base which is converted to its hydrochloride salt 580 mg (42%)ms m/z=526.

5(3(1-n-heptanoxy)-1,2,5-thiadiazol-4-yl)-1,4,5,6-tetrahyropyrimidineTrifluoroacetate

1-Triphenylmethyl-5(3(1-n-heptanoxy)-1,2,5-thiadiazol-4-yl)-1,4,5,6-tetrahydropyrimidineHCl (580 mg, 1 mmol) is dissolved in TFA (1 ml) and stirred overnight atroom temperature. The TFA is evaporated and the resulting dark oiltriturated with ether. After decanting the ether, the remaining solidsare recrystallized from methanol/ether to give 344 mg (87%) whitecrystals identified by 300 MHz nmr, ms m/z=360.

Example 231,4,5,6-Tetrahydro-5-(3-ethyl-1,2,4-oxadiazol-5-yl)pyrimidinetrifluoroacetate

Prepared by a procedure similar to Example 9, where sodium hydride (60%dispersion in mineral oil 56 mg, 1.4 mmol) and propionamidoxime (123 mg,1.4 mmol) were suspended in dry THF in an oven dried round bottom flaskwith stirring under nitrogen at 0° C. After 15 minutes stirring the icebath was removed and the grey suspension refluxed 45 minutes to give awhite suspension.1-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (540mg, 1.4 mmol) was added, dissolved in dry THF and reflux continued 18hours. The solvents were evaporated in vacno and the residue waschromatographed (silica, chloroform/methanol 9:1) to yield1-triphenylmethyl-1,4,5,6-tetrahydro-5-(3-ethyl-1,2,4-oxadiazol-5-yl)pyrimidine420 mg (70%). This product was dissolved in trifluoroacetic acid (2 mL),with stirring at room temperature for 24 hours. The yellow solution wasthen evaporated in vacuo, and the residue recrystallized frommethanol/ether to yield 144 mg (49%) white crystals, mp 116°-118° C.identified by 300 MHz nmr.

Example 241,4,5,6-Tetrahydro-5-(3-n-propyl-1,2,4-oxadiazol-5-yl)pyrimidinetrifluoroacetate

Prepared by a procedure similar to Example 9, where sodium hydride (60%dispersion in mineral oil 108 mg, 2.7 mmol) and butyramidoxime (276 mg,2.7 mmol) were suspended in dry THF in an oven dried round bottom flaskwith stirring under nitrogen at 0° C. After 15 minutes stirring the icebath was removed and the grey suspension refluxed 45 minutes to give awhite suspension.1-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (1.04g, 2.7 mmol) was added, dissolved in dry THF and reflux continued 18hours. The solvents were evaporated in vacuo and the residue waschromatographed (silica, chloroform/methanol, 9:1) to yield1-triphenylmethyl-1,4,5,6-tetrahydro-5-(3-n-propyl-1,2,4-oxadiazol-5-yl)pyrimidine785 mg (67%). This product was dissolved in triflouroacetic acid (2 ml),with stirring at room temperature for 24 hours. The yellow solution wasthen evaporated in vacuo, and the residue recrystallized frommethanol/ether to yield 240 mg (43%) white crystals, mp 126°-128° C.identified by 300 MHz nmr.

Example 251,4,5,6-Tetrahydro-5-(3-n-heptyl-1,2,4-oxadiazol-5-yl)pyrimidinetrifluoroacetate

Prepared by a procedure similar to Example 9, where sodium hydride (60%dispersion in mineral oil 96 mg, 2.4 mmol) and n-octylamidoxime (380 mg,2.4 mmol) were suspended in dry THF in an oven dried round bottom flaskwith stirring under nitrogen at 0° C. After 15 minutes stirring the icebath was removed and the grey suspension refluxed 45 minutes to give awhite suspension.1-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (910mg, 2.4 mmol) was added, dissolved in dry THF and reflux continued 18hours. The solvents were evaporated in vacuo and the residue waschromatographed (silica, chloroform/methanol, 9:1) to yield1-triphenylmethyl-1,4,5,6-tetrahydro-5-(3-n-heptyl-1,2,4-oxadiazol-5-yl)pyrimidine810 mg (69%). This product was dissolved in triflouroacetic acid (2 mL),with stirring at room temperature for 24 hours. The yellow solution wasthen evaporated in vacuo, and the residue recrystallized frommethanol/ether to yield 285 mg (49%) white crystals, mp 101°-102° C.identified by 300 MHz nmr.

Example 261,4,5,6-Tetrahydro-5-(3-n-butyl-1,2,4-oxadiazol-5-yl)pyrimidinetrifluoroacetate

Prepared by a procedure similar to Example 9, where sodium hydride (95%40 mg, 1.7 mmol) and valerylamidoxime (193 mg, 1.7 mmol) were suspendedin dry THF in an oven dried round bottom flask with stirring undernitrogen at 0° C. After 15 minutes stirring the ice bath was removed andthe grey suspension refluxed 45 minutes to give a white suspension.1-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (640mg, 1.7 mmol) was added, dissolved in dry THF and reflux continued 18hours. The solvents were evaporated in vacuo and the residue waschromatographed (silica, chloroform/methanol, 9:1) to yield1-triphenylmethyl-1,4,5,6-tetrahydro-5-(3-n-butyl-1,2,4-oxadiazol-5-yl)pyrimidine.This product was dissolved in triflouroacetic acid (2 mL), with stirringat room temperature for 24 hours. The yellow solution was thenevaporated in vacuo, and the residue recrystallized from methanol/etherto yield 150 mg (27%) white crystals, mp 98°-100° C. identified by 300MHz nmr.

Example 271,4,5,6-Tetrahydro-5-(3-n-pentyl-1,2,4-oxadiazol-5-yl)pyrimidinetrifluoroacetate

Prepared by a procedure similar to Example 9, where sodium hydride (95%40 mg, 1.7 mmol) and n-hexanamidoxime (217 mg, 1.7 mmol) were suspendedin dry THF in an oven dried round bottom flask with stirring undernitrogen at 0° C. After 15 minutes stirring the ice bath was removed andthe grey suspension refluxed 45 minutes to give a white suspension.1-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (640mg, 1.7 mmol) was added, dissolved in dry THF and reflux continued 18hours. The solvents were evaporated in vacuo and the residue waschromatographed (silica, chloroform/methanol, 9:1) to yield1-triphenylmethyl-1,4,5,6-tetrahydro-5-(3-n-pentyl-1,2,4-oxadiazol-5-yl)pyrimidine.This product was dissolved in triflouroacetic acid (2 mL), with stirringat room temperature for 24 hours. The yellow solution was thenevaporated in vacuo, and the residue recrystallized from methanol/etherto yield 110 mg (19%) white crystals, mp 97°-99° C. identified by 300MHz nmr.

Example 281,4,5,6-Tetrahydro-5-(3-n-octyl-1,2,4-oxadiazol-5-yl)pyrimidinetrifluoroacetate

Prepared by a procedure similar to Example 9, where sodium hydride (60%dispersion in mineral oil 104 mg, 2.6 mmol) and n-nonanamidoxime (448mg, 2.6 mmol) were suspended in dry THF in an oven dried round bottomflask with stirring under nitrogen at 0° C. After 15 minutes stirringthe ice bath was removed and the grey suspension refluxed 45 minutes togive a white suspension.1-Triphenylmethyl-1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine (1.0 g,2.6 mmol) was added dissolved in dry THF and reflux continued 18 hours.The solvents were evaporated in vacuo and the residue waschromatographed (silica, chloroform/methanol, 9:1) to yield1-triphenylmethyl-1,4,5,6-tetrahydro-5-(3-octyl-1,2,4-oxadiazol-5-yl)pyrimidine780 mg (60%). This product was dissolved in triflouroacetic acid (2 ml),with stirring at room temperature for 24 hours. The yellow solution wasthen evaporated in vacuo, and the residue recrystallized frommethanol/ether to yield 182 mg (30%) white crystals, mp 97°-99° C.identified by 300 MHz nmr.

The biological activity of representative compounds of the presentinvention was demonstrated using a number of tests. These tests includedusing ³ H-1-quinuclidinyl benzilate (QNB), ³ H-pirenzepine (PZ), ³H-oxotremorine M (OXO--M) to evaluate the effectiveness of the compoundsfor binding to muscarinic receptors. The potency and efficacy of thecompounds and their salts as selective M₁ agonists were evaluated bymeasuring phosphoinositide (PI) turnover in the cortex, PI turnover inthe hippocampus. Further details of the testing methods are set forthimmediately below.

Binding to Muscarinic Receptors

Binding was carried out essentially as described previously [Farrar, J.R. Hoss, W., Herndon, R. M. and Kuzmiak, M. Characterization ofMuscarinic Cholinergic Receptors in the Brains of Copper-Deficient Rats,J. Neurosci. 5:1083-1089, 1985.] Binding was determined indirectly bythe ability of compounds to compete with 50 pM [³ H]-1-quinuclidinylbenzilate ([³ H]-QNB) in a suspension of brain membranes. Each samplecontained approximately 10 pM receptors (2-4 μg/ml of protein) in 40 mMsodium/potassium phosphate buffer, pH 7.4 and varying concentrations ofcompound in a final volume of 10 ml. Samples were incubated for 2.0 hr.at room temperature and then filtered through glass fiber filters usinga Brandell cell harvester adapted for receptor binding work and thefilters washed twice with two 5-ml portions of cold buffer. Nonspecificbinding was evaluated by the inclusion of excess atropine in a separateset of samples. IC₅₀ values were determined from Hill plots of theinhibition data and are reported as means of three independentexperiments each performed in triplicate.

Other binding was determined indirectly by the ability of compounds tocompete with 1 nM ³ H-pirenzepine (³ H--PZ), or 3 nM ³ H-oxotremorine M(³ H--OXO--M) in a suspension of brain membranes. Each sample containedapproximately 0.1 mg/ml protein for ³ H--OXO--M in 20 mM Tris-Cl bufferwith 1 mM MnCl₂ and varying concentrations of compound in a final volumeof 10 ml. Samples were incubated 1 hr. for ³ H--PZ, and 15 minutes for ³H--OXO--M at room temperature and then filtered through glass fiberfilters using a Brandell cell harvester adapted for receptor bindingwork and the filters were washed twice with two 5-ml portions of coldbuffer. Nonspecific binding was evaluated by the inclusion of excessatropine in a separate set of samples. IC₅₀ values were determined fromHill plots of the inhibition data and are reported as means of threeindependent experiments each performed in triplicate.

Preparation of Brain Membranes

Rats were killed by cervical dislocation and their brains rapidlyremoved. Tissue was homogenized in 9 vol. (w/v) of a 40 mMsodium-potassium phosphate buffer solution (pH 7.4) buffer solution witha Brinkman Polytron homogenizer five times for 10 sec at 5 secintervals. The crude homogenate was subjected to centrifugation for 10min at 1000×g, the supernatant saved, and the pellet resuspended in 9vol. (w/v) of homogenization buffer and spun for another 10 min at1000×g. The supernatants were combined and spun again for 30 min at17,500×g. The resultant pellet was resuspended by homogenization in aTeflon-glass homogenizer in 10 vol. of buffer, and washed bycentrifugation at 17,500×g for 30 min. The final pellet was resuspendedby hand homogenization with a Teflon and glass homogenizer in buffer.The suspension was then divided into several portions and stored at -70°C.

Tissue Preparation

Male Long Evans rats (200-300 g) were decapitated and their brains wererapidly removed and dissected according to the method of Glowinski andIversen. [Glowinski, J. and Iversen, L. L., Regional Studies ofCatecholamines in Rat Brain I: The Disposition of [³ H]norepinephrine,[³ H]dopamine and [³ H]Dopa in Various Regions of the Brain, J.Neurochem, 13:655-669, 1966.] Brain slices (300×300 μm) were preparedusing a McIlwain tissue chopper and dispersed in Krebs-Hensleit buffer(KHB) containing 118 mM NaCl, 4.7 mM KCl, 1.3 mM CaCl₂, 1.2 mM KH₂ PO₄,1.2 mM MgSO₄, 25 mM NaHCO₃, and 11.7 mM glucose equilibrated with 95% 0₂/5% CO₂ to final pH of 7.4. The slices were gently agitated at 37° C. ina shaking water bath for 45 min with three changes to buffer.

Incorporation of [³ H]-Inositol and Agonist Stimulation of InositolPhosphate IP Formation

Immediately before each experiment, [³ H] inositol was purified bydrying under N₂ and passing a portion through a 1-ml column of DowexAG1-X8 (formate form) to remove contaminants. The continuous labelingparadigm essentially of Brown et al. (Brown, E. and Kendall, D. A. andNahorski, S. R., Inositol Phopholipid Hydrolysis in Rat Cerbral CorticalSlices: I. Receptor Charterisation, J. Neurochem., 42: 1379-1387, 1984)was selected because of its simplicity and sensitivity. Aliquots (25microliters) of tissue slices were pipetted into flat-bottomedBeckman-biovials (5-ml capacity) containing 0.3 mM [³ H]-inositol (15Ci/mmol) and 10 mM LiCl in 245 microliters of buffer. The vials werethen gassed, capped and incubated at 37° C. in a shaking water bath for30 min. At the end of 30 min, agonist (or buffer for the determinationof basal levels) was then added (30 microliters), and the incubationcontinued for an additional 45 min. The 45-min incubation period wasselected on the basis of the time course of labeled inositol phosphates([³ H]-IP's) accumulation under these conditions. The incubations werestopped by the addition of 0.94 ml of CHCl₃ /MeOH (1:2, V/V) followed by0.31 ml of CHCl₃ and 0.31 ml of H₂ O. The samples were mixed withvigorous shaking and spun at 1000×g for 10 min to separate organic andaqueous phases. Aliquots (750 microliter) of the upper aqueous phasewere removed for determination of [³ H]-IP's. In some cases 200 mlaliquots of the organic phase were removed, dried overnight and countedin 5 ml of scintillant (Amersham) for determination of [³ H]-inositolincorporation into phospholipids.

Assay of [³ H]-Labeled Inositol Phosphates

The amount of [³ H]-IP's formed in the assay was determined essentiallyaccording to Wreggett and Irvine (Wreggett, K. A. and Irvine, R. F., ARapid Separation Method for Inositol Phosphates and their Isomers,Biochem. J., 245:655-660, 1987) except that the separation of inositolphosphates was carried out using an Amersham Super Separator Manifold.Briefly, ACCELL QMA anion-exchange SEP-PAK's (Waters Associates)cartridges were converted into the formate form by washing first with 10ml of a solution of 1.0M-ammonium formate in 0.1M-formic acid, followedby 20 ml of distilled water. The sample loading and solution deliverywere performed by using disposable plastic syringes; an approximate flowrate of 10-15 ml/min was maintained. Total [³ H]-IP's were determined bythe "batch" method in which 750 microliter aliquots of the aqueous phaseobtained as described above was diluted to 3 ml with distilled water.The entire amount was loaded on to the ACCELL QMA anion-exchange SEP-PAKcartridge. The cartridge was then washed with 10 ml of distilled water,followed by 5 mM-disodium tetraborate. Radiolabeled IP's were theneluted with 1 ml of 0.6M-ammonium formate/0.06M formic acid/5mM-disodium tetraborate (pH 4.75) and 0.50 ml of this eluate was countedin 5 ml of aqueous counting scintillant. Under these conditions,carbachol produced a 3-5-fold increase in IP's accumulation over thebasal unstimulated value.

As representative of the compounds of this invention, and theirpharmaceutically acceptable salts, and also some other compositions, thetesting results of the following compounds, as produced in the examplesabove, are tabulated in Table I.

    ______________________________________                                        Exam-                                                                         ple   Compound Name:                                                          ______________________________________                                        1     1,4,5,6-tetrahydro-5-methoxycarbonylpyrimidine HBr                      2     1,4,5,6-tetrahydro-5-ethoxycarbonylpyrimidine HCl                       3     n-propyl 1,4,5,6-tetrahydropyrimidine-5-carboxylate HCl                 4     isopropyl 1,4,5,6-tetrahydro-pyrimidine-5-carboxylate HCl               5     benzyl 1,4,5,6-tetrahydropyrimidine-5-carboxylate HCl                   10    5-acetoxy-1,4,5,6-tetrahydropyrimidine HCl                              11    1-methyl-5-methoxycarbonyl-1,2,3,6-tetrahydropy-                               rimidine HCl                                                           14    2-amino-5-methoxycarbonyl-3,4,5,6-tetrahydropyridine                           HCl                                                                    15    2-amino-3-methoxycarbonyl-3,4,5,6-tetrahydropyridine                           HCl                                                                    16    2-amino-4-methoxycarbonyl-3,4,5,6-tetrahydropyridine                           HCl                                                                    18    2-trifluoromethyl-5-acetoxy-1,4,5,6-tetrahydropy-                              rimidine HCl                                                           19    2-methyl-5-acetoxy-1,4,5,6-tetrahydropyrimidine                         17    2-amino-6-methoxycarbonyl-3,4,5,6-tetrahydropyridine                           HCl                                                                    6     Propynyl 1,4,5,6-tetrahydropyrimidine-5-carboxylate HCl                 9     1,4,5,6-Tetrahydro-5-(3-methyl-1,2,4-oxadiazol-5-yl)                           pyrimidine trifluoroacetate                                            ______________________________________                                    

In the table, ³ H--QNB indicates general binding to muscarinic receptorsand the lower the number, the higher is the potency. ³ H--PZ indicatesbinding to muscarinic receptors and a preference for M₁ receptorsinvolved in memory and cognition. The lower the number for ³ H--PZ thehigher the potencies; the same is true for ³ H--OXO--M which indicatesagonist binding. In general, the higher the ratio of the value for ³H--PZ to the value for ³ H--OXO--M the better is the agonisticcharacteristic.

PI Cortex measures a relevant biochemical response for muscarinicreceptors linked to M₁, M₃, M₅ receptors and activity indicates it is anagonist at M₁ and/or M₃ and/or M₅ receptors. Higher activity numbersindicate higher efficacy relative to carbachol, a full agonist at allmuscarinic receptors.

Phosphoinositide turnover in the hippocampus indicates a biologicalresponse in an area of the brain where M₁ receptors predominate. Highernumbers indicate greater efficacy and selectivity at M₁ receptors.

                  TABLE I                                                         ______________________________________                                        Example .sup.3 H-QNB                                                                           .sup.3 H-PZ                                                                           .sup.3 H-OXO-M                                                                         PI Cortex                                   ______________________________________                                        1       9.2      3.9     0.09     131/100 μM                               2       1.9      0.73    0.16     150/100 μM                               3       2.1      1.33    1.085    7.1/100 μM                               4       3.5      2.26    1.76     7.2/100 μM                               5       ˜1 1.265   1.09     3.5/100 μM                               10      31.6     10      0.64                                                 11      25.1     15      2.4      182/1   mM                                  14      7.3      0.77    0.114    265/100 μM                               9       2.0      0.47    0.026    700/100 μM                               6       1.9                       230/100 μM                               15      83       13      >10      -5.5/100                                                                              μM                               16      130                       9.0/100 μM                               18      8.7      >10     >10                                                  19      100      >10     >10                                                  17      130      >10     >10      5.9/100 μM                               ______________________________________                                         Key:                                                                          .sup.3 HQNB, .sup.3 HPZ, and .sup.3 HOXO-M are IC.sub.50 values in            micromoles (μM); PI is maximal % response above baseline for a dose in     the range 50 μM to 1 mM.                                              

Phosphoinositide turnover in the hippocampus was measured on Examples 1,9, 10, 18 and 19. The values (as the above Key indicates for PI, i.e.maximal response/dosage) were: 237/1 mm (Ex. 1); 70/100 μM (Ex. 10);704/100 μM (Ex. 9); 0/50 μM (Ex. 18); and 0/50 μM (Ex. 19).

Interestingly, the 5-acetoxy-1,4,5,6-tetrahydropyrimidine HCl (Ex. 10)is effective at muscarinic receptors with acceptable binding data and isefficacious with respect to the PI response. In contrast, however,observe that 2-trifluoromethyl-5-acetoxy-1,4,5,6-tetrahydropyrimidineHCl (Ex. 18) has no PI response and even more significantly that2-methyl-5-acetoxy-1,4,5,6-tetrahydropyrimidine (Ex. 19), in addition tohaving virtually no PI response, shows extremely poor binding tomuscarinic receptors. Thus the unpredictable nature of this technologywill be readily apparent. Changing a hydrogen atom (Ex. 10) to a methylgroup (Ex. 19) resulted in the production of an inactive andunacceptable composition. Further along these lines note the dramaticdifference which results by simply changing the ring position of thesame moiety. The compound2-amino-5-methoxycarbonyl-3,4,5,6-tetrahydropyridine HCl (Ex. 14) has anunexpectedly superior PI response compared to the position isomers2-amino-3-methoxycarbonyl-3,4,5,6-tetrahydropyridine HCl (Ex. 15),2-amino-4-methoxycarbonyl-3,4,5,6-tetrahydropyridine HCl (Ex. 16), andcompared to 2-amino-6-methoxycarbonyl-3,4,5,6-tetrahydropyridine (Ex.17).

Based on the PI response data in Table I, it will be seen that propyl(Ex. 3), isopropyl (Ex. 4) and benzyl (Ex. 5) are not preferred esterforms for the 1,4,5,6-tetrahydropyrimidine-5-carboxylate compound or itssalt composition.

While the above describes and exemplifies the present invention it will,of course, be apparent that modifications are possible such as, forexample, using pro-drug forms of the compositions of this invention.These modifications, however, pursuant to the patent laws, including thedoctrine of equivalents, do not, however, depart from the spirit andscope of the present invention.

We claim:
 1. A compound having the formula (i), (ii), or (iii) below ora pharmaceutically acceptable salt thereof, ##STR4## wherein: A is H orNHR; R is H, alkyl of 1-7 carbon atom, --C(O)--R¹ or C(O)OR¹ ; andwherein Z is ##STR5## wherein X is O or S, and wherein R¹ is amonovalent hydrocarbon radical having 1-7 carbon atoms, R² is alkyl of1-8 carbon atoms, alkylthionlkyl or alkoxyalkyl of up to 8 carbon atomsor NHR, R³ is H or --CH₃, R₄, is H or an alkyl of 1-8 carbon atoms andwherein R⁵ is H, alkyl of 1-8 carbon atoms, alkoxy of 1-8 carbon atomsor an alkylthio group of 1-8 carbon atoms.
 2. The compound or salt ofclaim 1 wherein said compound or salt is that of (iii).
 3. The compoundor salt of claim 1 wherein said compound or salt is (i) or (ii).
 4. Thecompound or salt of claim 3 wherein said compound or salt is (i).
 5. Thecompound or salt of claim 3 wherein said compound or salt is (ii). 6.The compound or salt of claim 1 wherein Z is selected from I, II, III,IV, or VI.
 7. The salt or compound of claim 6 wherein the salt orcompound is (i) and Z is I.
 8. The compound or salt of claim 2 whereinsaid compound or salt is that of structure (iii) with the proviso that Ris --H.
 9. The compound of claim 1 where Z is I.
 10. The compound ofclaim 9 where Z is I and R² is an alkyl group of 1 to 4 carbon atoms.11. The compound of claim 9 where Z is I and R² is cyclopropyl, 2-methylpropyl, or 1-methyl butyl.
 12. The compound of claim 9 where Z is I andR² is alkoxy alkyl or alkylthioalkyl of 1-8 carbon atoms.
 13. In amethod of providing a therapeutic benefit to a mammal comprisingadministering to said mammal a drug in effective amounts to stimulate amuscarinic receptor so as to provide such benefit, the improvementwherein said drug is a compound of claim 1 or its pharmaceutically salt.14. A pharmaceutical preparation effective for stimulating a muscarinicreceptor, comprising a compound of claim 1, or a pharmaceuticallyacceptable salt thereof, together with a pharmaceutically acceptablesolid or liquid carrier.
 15. The compound, or salt, of claim 1 whereinsaid salt or compound is an M₁ muscarinic agonist.
 16. The preparationof claim 14 wherein in the compound or salt Z is selected from I, II,III, IV, V, VI.
 17. The preparation of claim 16 wherein said compound orsalt thereof is (i).
 18. The preparation of claim 17 wherein R and A areH.
 19. The preparation of claim 18 wherein Z is